Chemically filled polymeric articles

ABSTRACT

Solid gas-permeable synthetic polymeric articles are chemically filled with a filler compound formed in situ. These deposits are produced by diffusing one or more diffusion compounds into a solid gas-permeable polymer and reacting or decomposing the diffusion compound(s) to form deposits throughout the article. The compounds may be preferentially deposited in a planar zone of sheet material in an amount sufficient to cause the sheet to split.

United States Patent 1191 Hoffman, Jr.

CHEMICALLY FILLED POLYMERIC ARTICLES Inventor: Henry Tice Hoffman, Jr.,Trenton,

Assignee: American Can Company,

Greenwich, Conn.

Filed: May 16, 1972 Appl. N0.: 253,775

Related US. Application Data Continuation-impart of Ser. No. 868,626,Oct. 22, 1969, abandoned.

U.S. Cl 117/106 R, ll7/l06 A, 117/107 Int. Cl. B4411 l/02 Field ofSearch ll7/l06 R, 107.2 R, 68,

References Cited UNITED STATES PATENTS 3/1891 Erlwein ll7/DIG. i2

[ Nov. 19, 1974 2,771,378 ll/l956 Motter ll7/l06 R 2,898,229 8/1959 Herret 1 ll7/l06 R 3,294,059 12/1966 Barnes et al. 117/47 A 3,513,020 5/1970West 117/1311.s

Primary ExaminerCameron K. Weiffenbach Attorney, Agent, or Firm-RobertP. Auber; Ernestine C. Bartlett; George P. Ziehmer [5 7] ABSTRACT 9Claims, No Drawings CHEMICALLY FILLED POLYMERIC ARTICLES CROSS-REFERENCETO RELATED APPLICATION This application is a continuation-in-part of mypending application Ser. No. 868,626, filed Oct. 22, 1969, nowabandoned.

BACKGROUND OF THE INVENTION Solid synthetic polymeric articles are oftengaspermeable and/or permit solvent diffusion through the polymer. Therate of transmission of gases and/or solvent through such polymersvaries for different materials and the rate also may vary for materialsproduced by different manufacturing processes. It is often desired tominimize or totally eliminate such transmission. Mechanical filling ofpolymers has been attempted to reduce permeability with some effect.This has been accomplished by mechanically admixing a filler materialwith the resin and then fabricating the finished product. Suchmechanical filling is on a macro scale and affects the properties of thepolymer.

It is an object of the present invention to provide chemically filledpolymers wherein the filler material is deposited throughout thearticle. This provides an article having improved or differentproperties, i.e., different gas and/or solvent permeability, electricalproperties, chemical properties and/or physical properties.

SUMMARY OF THE INVENTION The present invention provides chemicallyfilled solid synthetic polymeric articles containing solid microdepositsthroughout the article. The solid microdeposits are filler compoundswhich are deposited from one or more diffusion compounds which arediffused into the solid gas-permeable synthetic polymeric article.

The present invention also provides a processfor filling continuous,solid gas-permeable synthetic polymeric articles comprising diffusing atleast one diffusion compound, and preferably two diffusion compoundsindividually from opposite sides of the article, thereinto, and thentransforming said diffusion compounds into an immobile deposit in saidsolid polymeric article.

The invention further provides a process for splitting a solidgas-permeable synthetic polymeric sheet comprising diffusing a diffusioncompound into a gaspermeable polymeric sheet and depositing a soliddeposit from said diffusion compound in at least one planar zone of saidsheet in an amount sufficient to split said sheet along said zone.

DETAILED DESCRIPTION OF THE INVENTION Gas and/or solvent permeability ofsolid synthetic polymeric articles is most often considered in thecontext of articles having relatively thin sections such as film, sheet,and wall sections of containers such as bottles. The present inventionis particularly directed to articles of this nature insofar as itprovides articles having substantially reduced gas and/or solventpermeability. The chemical filling may be accomplished to provide anarticle having specified physical, chemical, and- /or electricalproperties. In such instances, the design and size of sections of thefilled polymeric article may vary widely.

The chemically filled synthetic polymeric articles of the presentinvention may be prepared from such solid gas-permeable polymers aspolymeric fluorohalocarbon e.g., trifluorochloroethylene, an ionomer,notably an ionic copolymer of ethylene and an alpha, betaunsaturatedcarboxylic acid such as methacrylic acid in which the acid is partiallyneutralized to form a salt such as the zinc salt, polyamide,polycarbonate, polychloroprene, polyester, polyethylene, polypropylene,polystyrene, polyvinylchloride, rubber hydrochloride, silicone polymers,and copolymers thereof. Chemically filled polyethylene, polypropylene,polyvinylchloride, silicone and polycarbonate articles are of particularutility.

The solid gas-permeable synthetic polymeric articles are chemicallyfilled by diffusing at least one chemical compound into the polymericarticles and transforming said compound into a solid filler compounddeposited in the micro-interstices thereof. These filler compounds arepreferably inert, innocuous materials to produce gas-impermeablearticles. For the purposes of the present invention, it is not necessaryto determine the physical state, when deposited, of the compound makingup the filler deposits. However, the deposits are immobile and of acompound which is a solid when in bulk, and the amount and chemicalnature of the deposits may be confirmed by careful weighing of thefilled polymer shape (after outgassing and cleaning its surfaces), andby analytical procedures such as infrared spectroscopy, as indicated inthe examples hereinbelow. Neither is it necessary to determine thedimensions of the micro-interstices within which the deposits form;since as disclosed hereinbelow the bodies to be filled are continuousthin shapes of apparently homogeneous solid polymer, the intersticesfilled by the deposits must be of microscopic or even. moleculardimensions, and the filler material formed the-rein thus maybedesignated at least initially as micro-deposits."

A filler compound" deposit may be formed by reacting two compounds inthe solid polymeric article as a matrix. The two compounds may bediffused in from opposite sides of the article or may be diffusedsequentially from the same side. One of the said compounds, e.g.,atmospheric oxygen or water vapor, may be diffused in the solidpolymeric article as a result of atmospheric exposure after the firstcompound is diffused in. Such reactions and concomitant deposition on .amicro scale are illustrated in the following equations.

2Ni(CO), 0 2Ni0 sco Ni(CO), Ni 4co Useful filler compounds include thehalides and oxides of metals. The said metals are preferably the GroupIII A metals, especially aluminum and boron; the Group IVmctalsespccially tin and silicon (Group W8) and titanium (Group IVA);and the transition metals in Groups other than Groups lll and 1V. e.g.,nickel, iron, etc. (Group VIII).

The diffusion of a decomposable compound into the permeable polymerarticle and subsequent decomposition is illustrated by the diffusion ofnickel carbonyl with decomposition (in the absence of oxygen) to depositnickel as a filler. For purposes of the present application, depositionofa filler element is included as a species of a filler compound and isencompassed by said term.

The compounds which are diffused into the solid gaspermeable polymer,referred to herein as diffusion compounds," are exposed to the surfaceof the solid gas-permeable polymer in their gaseous or liquid state. Thepreferred compounds are those that are in the gaseous state and thoseliquids having a substantial vapor pressure under the applied processconditions, as for example, silicon tetrachloride, a fuming liquid atroom temperature.

The compounds which may be utilized to form the deposited fillercompound are those that will diffuse into the solid gas-permeablepolymeric article. They should not degrade the polymeric article and,therefore, preferably should not react with a solid matrix.

The mechanism by which compounds diffuse into solid gas-permeablepolymeric materials is not definitively known. The solid polymericmaterials, which are treated in accordance with the invention, areapparently uniform that is, apparently homogeneous solid bodies. Theexamples set out hereinbelow utilize extruded thermoplastic material insheet form, or utilize Boston round bottles of thermoplastic materialmolded conventionally in tubular shapes, and are of uniform solidstructure.

The mechanisms by which gases, or the vapors from volatile liquids, maypenetrate into or pass through solid bodies are generally wellrecognized. Such mechanisms are discussed, for example, by Yasuda andStannet in Encyclopedia of Polymer Science and Technology, lntersciencePublishers, New York (1965), volume 2, in a section on vapor barriers,pages 316-317. Porous media such as paper, fabrics, foamed plastics, andsome cellulosic membranes permit permeation by capillary or convectiveflow through pores and canals. However, homogeneous films of polymericmaterials require a pressure difference, or gradient of partialpressure, of the vapor involved, the mechanism of transmission of vaporthrough the film thus being of the diffusion type. While some solidpolymeric sheets appear to have strata of different diffusioncharacteristics (discussed hereinbelow), they are nevertheless solidthroughout, and free of pores which would permit capillary or convectiveflow. As used herein, the term solid polymeric article" will beunderstood to refer to polymeric materials of essentially uniformnonporous structure in which vapor permeation occurs through a diffusionmechanism.

Various mechanisms have been postulated which include diffusion inapparently solid homogeneous material along boundaries between adjacentand similarly oriented crystal structures; between adjacent anddissimilarly oriented crystal structures; through or along latticediscontinuities; through regions of non-oriented or amorphous material;and by vacancy migration. The art sometimes has referred to solidgas-permeable polymeric materials, which will over a period of timepermit passage (by diffusion) of gases and sometimes of solutions, asbeing micro-porous. The definitively known facts are limited to theknowledge that solid gaspermeable polymeric materials permit diffusionof gaseous compounds and certain volatile compounds in the liquid statewhen in contact therewith. These compounds, which are diffused into andthrough the solid gas-permeable polymers, are referred to herein asdiffusion compounds. The actual physical state of such diffusioncompounds in the solid gas-permeable polymer matrix is not definitivelyknown.

The phrase transforming said diffusion compound into solid materialdeposited in said solid polymeric article" includes formation of solidby chemical means. c.g., as a reaction deposit. by decomposition, etc.

These considerations affect the uniformity or nonuniformity of thedeposit of filler compound throughout the polymeric article. Non-uniformdeposition may be achieved when filling polymeric articles havingportions of different cross section size and/or orientation and/orstructure.

Filler compound may also be deposited in a nonuniform manner throughsuch apparently uniform solid polymeric articles as sheet and film. Theobtention of non-uniform filling resultant from non-uniform structure isillustrated by polyethylene which is considered to have both crystallineand amorphous regions. It has been postulated that diffusion occursthrough the amorphous regions. Accordingly, it would be expected thatthe micro-deposition is preferential in the areas in which there is thelargest amount of diffusion of the diffusion compound. Non-uniformitymay be effected by controlling the conditions under which the diffusioncompound is diffused into the polymeric article.

The present invention has provided evidence that extruded polyethylenefilm is built up of multiple well defined lamellar layers of crystallinematerial. Under selective conditions it is possible to preferentiallyform deposits in at least one layer parallel to the surface of the film.It is postulated that the deposit is formed in a region between layersof more crystalline material. The deposition can be continued untilsufficient filler compound has been deposited to cause the polyethylenefilm to split into layers along the deposition zone. The thickness ofthe polyethylene layer(s) split off from the film can be controlled byvarying the process conditions. In this instance, the initialmicro-deposits of filler material increase to become macro-deposits.

The procedure may be utilized for forming nonuniform deposits withmaximum concentration offiller compound at several different sites inthe polymeric article by sequentially varying the deposition conditions.

The chemical filling is resultant from the diffusion and subsequentreaction of the diffusion compound or compounds to deposit a solidfiller throughout the solid gas-permeable synthetic polymeric article.The term throughout" refers to the contiguous gas-permeable regions ofthe polymeric article into which the diffusion compound is diffused.

The temperature of the solid gas-permeable polymeric article when thediffusion compound is diffused into the article may vary from ambienttemperatures or even refrigerated temperatures up to elevatedtemperatures. The elevated temperatures should not be sufficiently highto cause distortion of the solid polymeric article.

The rate of diffusion of the diffusion compound into and through thesolid gas-permeable polymeric article and the consequent amount andsitus of filler compound deposited are affected by the pressure of thediffusion compound at the exposed surface of said solid gas-permeablepolymeric article. For most diffusion compounds, the higher the pressureand the higher the temperature, the greater the diffusion rate into thesolid gas-permeable polymeric article. When the diffusion compound is ina mixture or solution, agitation of said mixture or solution tends toincrease the diffusion rate into the solid gas-permeable polymericarticle. The

mation of the presence of ammonium chloride. Examination of the surfaceof the filled polyethylene film was made with a scanning microscope anddetermined that the filling causes a marked change in surface topogra- 5phy. The unfilled control had a relatively smooth surface. Elliptical oroval craters (or elevations) were 223 212 finlhs 2r= ,.9i! fillsl.flm-

The weight gain, and GTR data for carbon dioxide and oxygen. of theammonium chloride-filled film are molecular size of the diffusioncompound and the solu- 10 reported in thefollow ng tablei Sample FillingWeight GTR cc.STP[m [24 hrlatm! Timeihr) -Gain ting.) C92 Red. 02'%Red;*

Control l8,740 4,120

'% reduction GTRr mm-qh' m m/ ummn Slli'l l' ..?"RT?9'.. P"= s Lw bilitythereof in the solid gas-permeable polymeric arti- EXAMPLE 2 cle alsoaffect the diffusion rate and amount of filler compound deposited. Itwill appear, as suggested hereinabove, that a substantial period of timeis required to permit passage by diffusion of reaction compounds wellinto the interior of even thin homogeneous bodies; the examples set outhereinbelow indicate that treatment period of the order of an hour ormore is required for the time to be sufficient to permit substantialdiffusion into the body.

As indicated hereinabove, the solid polymeric articles utilized inaccordance with the invention are thin, continuous, and apparentlyhomogeneous or uniform bodies of solid gas-permeable synthetic polymer.The invention is further illustrated by the following examples. Allparts and percentages throughout the application are by weight unlessotherwise specified.

EXAMPLE 1 Disc-shaped samples 6 inches in diameter of a low densitypolyethylene film, extruded with a nominal thickness of 5 mils, werefilled with ammonium chloride by reacting ammonia and hydrogen chloride.An impregnation cell was made from two 5-inch glass funnels. The lips ofthe funnels were ground to provide a flat surface and the cell wasformed by clamping the lips of the funnels together. For impregnation, adisc of the polyethylene film, sandwiched between rubber gaskets, wasclamped between the lips of the funnels to form two compartments withinthe cell. Streams of hydrogen chloride and ammonia were run into theopposite chambers at atmospheric pressure. Thus the two diffusioncompounds, which react within the body of polymeric material to form thefiller compound, are diffused into the body individually from oppositesides thereof. Gas flow was maintained during impregnation. Samples wereprepared with various impregnation times..Sample weight gains weredetermined, and gastransmission rate (GTR) measurements were made by theDow Cell Method (ASTM D-l434-66). Infrared its. Infrared spectra of thesamples gave positive confin- 35 mil film was split into two layers. Thethickness ofeach of these layers in mils (thousandths of an inch) andthe pressure of the ammonia and hydrogen chloride are re- PPIFE! i9 hllqw a .ialzlsg Thickness of Layers Sample NH;, Press. HCl Press.

(psig) (psig) Nl-l side HCI side l l6 16 2.3 1.6 2 l6 10 2.6 L4 3 16 2.52.8 1.0 4 7 5 2.1 1.5 5 2.5 7.5 2.0 1.7 6 2.5 lb 1.8 2.1

EXAMPLE 3 Boston round bottles (2 ounce) of low density poly- O ethylenewere chemically filled by exposure to silicon tetrachloride vapors onthe outside and ammonia vapors on the inside for about hours. Diffusionof carbon tetrachloride through the treated bottle and through a controlresulted in a transmission rate of 0.2 gram per day for the treatedbottle compared with 2 grams per day for the untreated bottle.

EXAMPLE 4 Boston round bottles (2 ounce) of low density polyethylenewere filled with Ti(iPrO) The bottles were capped. The diffusion ratefor the titanium isopropoxide was 1.4 mg. per day. Hydrolysis of theTi(iPrO) on contact with water vapor in the polymer wall or at the outerside yields TiO Other bottles were filled with carbon tetrachloridecontaining a small amount of Ti(iPrO) After standing for 22 days, thebottle sidewalls did not show signs of paneling (inward collapse).Identical bottles filled with the same amount of carbon tetrachlorideonly show signs of paneling after 22 days.

EXAMPLE polypropylene, polyvinyl chloride, silicones, and polycarbonatesresults in chemically filled synthetic polymeric articles such as thoseillustrated in the examples.

Although the examples generally have utilized percentage reduction ofthe gas-permeability as a measure of the chemical filling, the processof the present invention also produces chemically filled syntheticpolymeric articles having different physical, electrical, and- /orchemical properties than the solid gas-permeable polymer from which thefilled article was prepared. The changed physical properties areillustrated by the increase of compressive strength as a result of thechemical filling. Deposition of a filler compound such as tin oxide ornickel oxide or nickel metal may change the electrical properties.Chemically filled articles of the present invention may be filled with achemical which upon exposure to a specified atmosphere slowly reactswith the said atmosphere and provides controlled release of theconsequent reaction product.

The foregoing illustrate the versatility of the process of the presentinvention and of the novel chemically filled products produced thereby.

What is claimed is:

1. The process for filling a continuous, apparently homogeneous, thinsolid gas-permeable polymeric article comprising the step of diffusingtwo diffusion compounds in the gaseous state into said thin articleindividually from opposite sides thereof to effect reaction between saiddiffusion compounds within the said solid article and resultantdeposition therewithin of an immobile reaction compound.

2. The process of claim 1, in which said diffusing is continued for aperiod of the order ofan hour or more.

3. The process of claim 1, in which said thin solid article is composedof at least one synthetic polymer selected from the group consisting ofpolymeric fluorohalocarbon, ionomer, polyamide, polycarbonate,poly(chloroprene), polyester, polyethylene, polypropylene, polystyrene,poly(vinyl chloride), rubber hydrochloride, solid silicones, andcopolymers formed from the monomers of at least two of said polymers.

4. The process of claim 1, in which said thin, solid article is ofpolyethylene.

5. The process of claim 1, in which the filler reaction compound isdeposited within the solid material of said continuous thin articlewithout effecting separation of said article into layers.

6. The process of claim 1, in which one of said diffusion compounds isammonia and the other of said diffusion compounds is a silicon halide.

7. The process of claim 6, in which said halide is silicontetrachloride.

8. The process of claim 1, in which said two diffusion compounds areammonia and hydrogen chloride.

9. The process of claim 8, in which said thin, solid article subjectedto said two diffusion compounds is a

1. THE PROCESS FOR FILLING A CONTINUOUS, APPARATUS HOMOGENEOUS, THINSOLID GAS-PERMEABLE POLYMERIC ARTICLE COMPRISING THE STEP OF DIFFUSINGTWO DIFFUSION COMPOUNDS IN THE GASEOUS STATE INTO SAID THIN ARTICLEINDIVIDUALLY FROM OPPOSITE SIDES THEREOF TO EFFECT REACTION BETWEEN SAIDDIFFUSION COMPOUNDS WITHIN THE SAID ARTICLE AND RESULTANT DEPOSITIONTHEREWITHIN OF AN IMMOBILE REACTION COMPOUND.
 2. The process of claim 1,in which said diffusing is continued for a period of the order of anhour or more.
 3. The process of claim 1, in which said thin solidarticle is composed of at least one synthetic polymer selected from thegroup consisting of polymeric fluorohalocarbon, ionomer, polyamide,polycarbonate, poly(chloroprene), polyester, polyethylene,polypropylene, polystyrene, poly(vinyl chloride), rubber hydrochloride,solid silicones, and copolymers formed from the monomers of at least twoof said polymers.
 4. The process of claim 1, in which said thin, solidarticle is of polyethylene.
 5. The process of claim 1, in which thefiller reaction compound is deposited within the solid material of saidcontinuous thin article without effecting separation of said articleinto layers.
 6. The process of claim 1, in which one of said diffusioncompounds is aMmonia and the other of said diffusion compounds is asilicon halide.
 7. The process of claim 6, in which said halide issilicon tetrachloride.
 8. The process of claim 1, in which said twodiffusion compounds are ammonia and hydrogen chloride.
 9. The process ofclaim 8, in which said thin, solid article subjected to said twodiffusion compounds is a polyethylene article.